1. Field of the Invention
The present invention relates to a cathode ray tube device including a projection cathode ray tube having an electron gun for emitting a single electron beam toward a phosphor screen and, more particularly, to a cathode ray tube device constructed to prevent the deviation between the center of the phosphor screen of a projection cathode ray tube and the center of a projection lens as well as to an image display apparatus using the cathode ray tube device.
2. Description of the Related Art
In general, a projection color image display apparatus such as a projection color TV set employs three projection cathode ray tube devices for respectively reproducing images of primary colors, i.e., red, green and blue, and projects three primary color images obtained from these three projection cathode ray tube devices onto a screen by using an optical lens or a mirror on an enlarged scale and superposes the three primary color images to form a color image on the screen. Incidentally, there are projection cathode ray tubes having phosphor screens having diagonal sizes of 5.5 inches, 7 inches and the like, and projection TV sets employ screens having diagonal sizes of approximately 40–70 inches.
FIG. 11 is a schematic cross-sectional view aiding in describing an example of the construction of a related-art projection cathode ray tube device which is used in a projection color image display apparatus such as the above-mentioned projection color television set. In FIG. 11, reference numeral 1 denotes a panel portion, reference numeral 2 denotes a funnel portion, reference numeral 3 denotes a neck portion, and reference numeral 4 denotes a stem portion, and the panel portion 1, the funnel portion 2, the neck portion 3 and the stem portion 4 constitute an evacuated envelope 5. Reference numeral 6 denotes an electron gun, and this electron gun 6 is disposed in the neck portion 3. The panel portion 1 has a faceplate 11 and a sidewall 12 which extends toward the funnel portion 2, and the faceplate 11 is provided with a phosphor screen 11b on an inside surface 11a, and light emitted from the phosphor screen 11b is radiated outwardly from an outside surface 11c. 
The inside surface 11a of the faceplate 11 has a spherical form having the center of curvature on the side of the outside surface 11c, and its convex surface is disposed on the side of the electron gun 6. The outside surface 11c is flat. The electron gun 6 has a plurality of electrodes, and emits a single electron beam toward the phosphor screen 11b to excite phosphors to cause them to emit light. In FIG. 11, reference numeral 13 generally denotes a cathode ray tube.
Reference numeral 14 denotes a deflector which includes a deflection yoke, a convergence yoke and the like. The deflector 14 is fitted on a transition portion between the neck portion 3 and the funnel portion 2 of the cathode ray tube 13, and the electron beam emitted from the electron gun 6 is deflected in the x direction (the horizontal direction) and they direction (the vertical direction) by the deflection yoke of the deflector 14 and is made to impinge on the phosphor screen 11b formed on the inside surface 11a of the faceplate 11 of the panel portion 1, thereby forming a required image.
Reference numeral 15 denotes a lens assembly, and this lens assembly 15 is disposed in opposition to the outside surface 11c of the faceplate 11 and is constructed to project an image on the phosphor screen 11b on a screen (not shown) on an enlarged scale. The lens assembly 15 is coupled to the cathode ray tube 13 via a coupler 16. This coupling is carried out after the completion of alignment of the central axis of the lens assembly 15 and the center of the phosphor screen 11b formed on the inside surface 11a of the faceplate 11.
It is to be noted that the coupling of the cathode ray tube 13 and the coupler 16 in this coupling structure can adopt, for example, means using an engagement unit disclosed in Patent Document 1.
Reference numeral 17 denotes a refrigerant liquid, and this refrigerant liquid 17 has the function of coming into contact with and cooling the outside surface 11c of the faceplate 11 of the panel portion 1. This refrigerant liquid 17 is held in a space which is surrounded by the coupler 16, the lens assembly 15 and the outside surface 11c of the faceplate 11.
Reference numeral 18 generally denotes a cathode ray tube device.
As one related art associated with the faceplate of this kind of projection cathode ray tube device, Patent Document 2 discloses a construction in which the obverse side of the front wall of a bulb is formed as a concave surface and the inside surface of the same is formed as a convex surface.
As another related art associated with a lens system which projects an image of the surface of a concave object onto a flat display screen, Patent Document 3 discloses a content including a construction in which a faceplate is formed to have a construction similar to that disclosed in Patent Document 2.
As yet another related art associated with an image projecting system provided with a multi-element projection lens system, Patent Document 4 discloses a construction in which a faceplate is formed to have a construction similar to that disclosed in Patent Document 2 and a plate-shaped holding unit through which to pass a coolant is disposed between the faceplate and a lens.
Patent Document 5 discloses the illustration of a faceplate formed to have a construction similar to that disclosed in Patent Document 2.
Patent Document 1 is JP-A-62-8423.
Patent Document 2 is JP-A-58-44657.
Patent Document 3 is JP-A-60-43627.
Patent Document 4 is JP-A-63-148221.
Patent Document 5 is UK Patent No. 2,091,898.